Address feedback

benchmarks/src/main/java/reactor/core/observability/micrometer/MicrometerMeterListenerConfigurationResolveTagsBenchmark.java

@@ -40,16 +40,17 @@
 @OutputTimeUnit(TimeUnit.NANOSECONDS)
 @State(Scope.Benchmark)
 public class MicrometerMeterListenerConfigurationResolveTagsBenchmark {
-	@Param({"1", "2", "5", "10"})
-	private int distinctTagCount;
-
-	@Param({"1", "2", "5", "10"})
-	private int totalTagCount;
+	@Param({"1|1", "1|2", "1|5", "1|10", "2|2", "2|5", "2|10", "5|5", "5|10", "10|10"})
+	private String testCase;
 
 	private Publisher<Void> publisher;
 
 	@Setup(Level.Iteration)
 	public void setup() {
+		String[] arguments = testCase.split("\\|", -1);
+		int distinctTagCount = Integer.parseInt(arguments[0]);
+		int totalTagCount = Integer.parseInt(arguments[1]);
+
 		publisher = addTags(Mono.empty(), distinctTagCount, totalTagCount);
 	}
 

gradle/libs.versions.toml

@@ -9,7 +9,7 @@
 # Baselines, should be updated on every release
 baseline-core-api = "3.6.11"
 baselinePerfCore = "3.6.11"
-baselinePerfCoreMicrometer = "1.1.9"
+baselinePerfCoreMicrometer = "1.1.10"
 baselinePerfExtra = "3.5.2"
 
 # Other shared versions

reactor-core-micrometer/src/main/java/reactor/core/observability/micrometer/MicrometerMeterListenerConfiguration.java

@@ -93,6 +93,7 @@ static Tags resolveTags(Publisher<?> source, Tags tags) {
 		Scannable scannable = Scannable.from(source);
 
 		if (scannable.isScanAvailable()) {
+			// `Tags#and` deduplicates tags by key, retaining the last value as required.
 			List<Tag> discoveredTags = scannable.tags()
 				.map(t -> Tag.of(t.getT1(), t.getT2()))
 				.collect(Collectors.toList());

reactor-core-micrometer/src/main/java/reactor/core/observability/micrometer/MicrometerObservationListenerConfiguration.java

@@ -70,6 +70,7 @@ static KeyValues resolveKeyValues(Publisher<?> source, KeyValues tags) {
 		Scannable scannable = Scannable.from(source);
 
 		if (scannable.isScanAvailable()) {
+			// `KeyValues#and` deduplicates tags by key, retaining the last value as required.
 			List<KeyValue> discoveredTags = scannable.tags()
 				.map(e -> KeyValue.of(e.getT1(), e.getT2()))
 				.collect(Collectors.toList());

reactor-core/src/main/java/reactor/core/Scannable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2023 VMware Inc. or its affiliates, All Rights Reserved.
+ * Copyright (c) 2017-2024 VMware Inc. or its affiliates, All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -627,7 +627,9 @@ default Stream<Tuple2<String, String>> tags() {
 	 *
 	 * @return a {@link Map} of deduplicated tags from this {@link Scannable} and its reachable parents
 	 * @see #tags()
+	 * @deprecated Micrometer APIs generally deduplicate tags and key-value pairs by default, so for related use cases prefer {@link #tags()}.
 	 */
+	@Deprecated
 	default Map<String, String> tagsDeduplicated() {
 		return tags().collect(Collectors.toMap(Tuple2::getT1, Tuple2::getT2,
 			(s1, s2) -> s2, LinkedHashMap::new));

reactor-core/src/main/java/reactor/core/publisher/FluxMetrics.java

@@ -295,6 +295,7 @@ static Tags resolveTags(Publisher<?> source, Tags tags) {
 		Scannable scannable = Scannable.from(source);
 
 		if (scannable.isScanAvailable()) {
+			// `Tags#and` deduplicates tags by key, retaining the last value as required.
 			List<Tag> discoveredTags = scannable.tags()
 				.map(t -> Tag.of(t.getT1(), t.getT2()))
 				.collect(Collectors.toList());